It has been a long time since I did this and don't remember precisely. I remember removing screws on the top of the truck as well. Oh, look up a bit thers is a picture of the power truck apart. You'll notice the screws that pass from the top of the truck to the electrical pickups below must be removed. Then it falls apart. You may have to remove the rupper around the openings forward and rear of the motor.
Let me know how you did.